1. Field of the Invention
The invention relates methods to control and prevent tick infestations in treated non-bovine animals, including domestic dogs, which further protects the animals against the transmission of tick-borne pathogens. Vaccine compositions are prepared from the aquaporin protein from the cattle tick, Rhipicephalus microplus, or from a nucleic acid construct comprising a nucleic acid sequence encoding this aquaporin protein.
2. Description of the Prior Art
Ticks pose a significant risk to the health and welfare of warm-blooded animals as the vectors for a large number of pathogenic agents, including protozoan parasites, viruses and bacteria. For instance, the brown dog tick, Rhipicephalus sanguineus, is the primary reservoir and vector of canine ehrlichiosis, a lethal disease caused by the blood-borne intracellular bacterial pathogen, Ehrlichia canis, and canine babesiosis, caused by the intraerythrocytic protozoan parasites Babesia canis and Babesia gibsoni. Canine ehrlichiosis occurs throughout the world and is endemic in the United States, infecting dogs of all breeds and ages. Cats and humans may be infected with E. canis as well. The brown dog tick can also transmit Rocky Mountain spotted fever to humans. Ticks are also carriers of a number of other common tick-borne infectious disease agents such as tick-borne encephalitis virus, Crimean-Congo hemorrhagic fever virus, Nairobi sheep virus, Borrelia burgdorferi (the agent of Lyme disease), Theileria parva (the agent of East Coast fever), and parasites of the genus Babesia (including the agents of babesiosis or cattle fever in bovine), as well as other injurious effects that have major impacts in human and veterinary medicine.
Presently, efforts to control these pests have primarily relied upon the use of pesticides. However, an increase in the resistance of ticks to approved acaricides and insecticides threatens efforts to control these pests in the U.S. and elsewhere.
As a result of the spread of pesticide-resistant strains of these and other ticks and flies, there is a growing need to develop improved tools for their control. Attempts have been made to use immunological means of control through vaccine technology. Some success has been met in identifying certain protective antigens of arthropod parasites as being potential vaccine candidates, but only a few have as yet come to commercial fruition, most notably the BM86 vaccine for the cattle tick Rhipicephalus (Boophilus) microplus. Despite these developments, there is nonetheless a continuing need for arthropod parasite vaccines and in particular for a vaccine which may be used against ticks, including the brown dog tick.